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Data from: Divergence in mating signals correlates with genetic distance and behavioural responses to playback
Sosa-López, J. Roberto; Martinez Gomez, Juan E.; Mennill, Daniel J. — 2015-11-19 Animals use acoustic signals to defend resources against rivals and attract breeding partners. As with many biological traits, acoustic signals may reflect ancestry; closely related species often produce more similar signals than do distantly related species. Whether this similarity in acoustic signals is biologically relevant to animals is poorly understood. We conducted a playback experiment to measure the physical and vocal responses of male songbirds to the songs of both conspecific and allopatric-congeneric animals that varied in their acoustic and genetic similarity. Our subjects were territorial males of four species of neotropical Troglodytes wrens: Brown-throated Wrens (Troglodytes brunneicollis), Cozumel Wrens (T. beani), Clarion Wrens (T. tanneri), and Socorro Wrens (T. sissonii). Our results indicate that birds respond to playback of both conspecific and allopatric-congeneric animals; that acoustic differences increase with genetic distance; and that genetic divergence predicts the strength of behavioural responses to playback, after removing the effects of acoustic similarity between subjects’ songs and playback stimuli. Collectively, these results demonstrate that the most distantly related species have the most divergent songs, that male wrens perceive divergence in fine structural characteristics of songs, and that perceptual differences between species reflect evolutionary history. This study offers novel insight into the importance of acoustic divergence of learned signals and receiver responses in species recognition.
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Data from: Hot temperatures during the dry season reduce survival of a resident tropical bird
Woodworth, Brad K.; Norris, D. Ryan; Graham, Brendan A.; Kahn, Zachary A.; Mennill, Daniel J.; Woodworth, Bradley K. — 2018-04-13 Understanding how climate change will shape species distributions in the future requires a functional understanding of the demographic responses of animals to their environment. For birds, most of our knowledge of how climate influences population vital rates stems from research in temperate environments, even though most of the Earth’s avian diversity is concentrated in the tropics. We evaluated effects of Southern Oscillation Index (SOI) and local temperature and rainfall at multiple temporal scales on sex-specific survival of a resident tropical bird, the Rufous-and-White Wren Thryophilus rufalbus, studied over 15 years in the dry forests of northwestern Costa Rica. We found that annual apparent survival of males was 8% higher than females, more variable over time, and responded more strongly to environmental variation than female survival, which did not vary strongly with SOI or local weather. For males, mean and maximum local temperatures were better predictors of survival than either rainfall or SOI, with high temperatures during the dry season and early wet season negatively influencing survival. These results suggest that, even for species adapted to hot environments, further temperature increases may threaten the persistence of local populations in the absence of distributional shifts.
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Data from: Dispersal influences genetic and acoustic spatial structure for both males and females in a tropical songbird
Graham, Brendan A.; Heath, Daniel D.; Mennill, Dan J.; Mennill, Daniel J. — 2018-09-22 1. Animals exhibit diverse dispersal strategies, including sex-biased dispersal, a phenomenon common in vertebrates. Dispersal influences the genetic structure of populations as well as geographic variation in phenotypic traits. Patterns of spatial genetic structure and geographic variation may vary between the sexes whenever males and females exhibit different dispersal behaviours. 2. Here, we examine dispersal, spatial genetic structure, and spatial acoustic structure in Rufous-and-white Wrens, a year-round resident tropical bird. Both sexes sing in this species, allowing us to compare acoustic variation between males and females, and examine the relationship between dispersal and song sharing for both sexes. 3. Using a long-term dataset collected over an 11-year period, we used banding data and molecular genetic analyses to quantify natal and breeding dispersal distance in Rufous-and-white Wrens. We quantified song-sharing and examined whether sharing varied with dispersal distance, for both males and females. 4. Observational data and molecular genetic analyses indicate that dispersal is female-biased. Females dispersed farther from natal territories than males, and more often between breeding territories than males. Furthermore, females showed no significant spatial genetic structure, consistent with expectations, whereas males showed significant spatial genetic structure. Overall, natal dispersal appears to have more influence than breeding dispersal on spatial genetic structure and spatial acoustic structure, given that the majority of breeding dispersal events resulted in individuals moving only short distances. 5. Song sharing between pairs of same-sex animals decreases with the distance between their territories for both males and females, although males exhibited significantly greater song-sharing than females. 6. Lastly, we measured the relationship between natal dispersal distance and song sharing. We found that sons shared fewer songs with their fathers the farther they dispersed from their natal territories, but that song sharing between daughters and mothers was not significantly correlated with natal dispersal distance. 7. Our results reveal cultural differences between the sexes, suggesting a relationship between culture and sex-biased dispersal
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Data from: Parallel evolutionary forces influence the evolution of male and female songs in a tropical songbird
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Graham, Brendan A.; Heath, Daniel D.; Walter, Ryan P.; Mark, Melissa M.; Mennill, Daniel J. — 2018-04-04 Given the important role that animal vocalizations play in mate attraction and resource defence, acoustic signals are expected to play a significant role in speciation. Most studies, however, have focused on the acoustic traits of male animals living in the temperate zone. In contrast to temperate environments, in the tropics it is commonplace for both sexes to produce complex acoustic signals. Therefore tropical birds offer the opportunity to compare the sexes and provide a more comprehensive understanding of the evolution of animal signals. In this study we quantified patterns of acoustic variation in Rufous-and-white Wrens (Thryophilus rufalbus) from five populations in Central America. We quantified similarities and differences between male and female song by comparing the role that acoustic adaptation, cultural isolation, and neutral genetic divergence have played in shaping acoustic divergence. We found that males and females showed considerable acoustic variation across populations, although females exhibited greater population divergence than males. Redundancy analysis and partial-redundancy analysis revealed significant relationships between acoustic variation and ecological variables, genetic distance, and geographic distance. Both ambient background noise and geographic distance explained a high proportion of variance for both males and females, suggesting that both acoustic adaptation and cultural isolation influence song. Overall, our results indicate that parallel evolutionary forces act on male and female acoustic signals and highlight the important role that cultural drift and selection play in the evolution of both male and female songs.

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(auteur : Mennill, Daniel J.)

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